title: The structure of NtdA, a sugar aminotransferase involved in the kanosamine biosynthetic pathway in Bacillus subtilis, reveals a new subclass of aminotransferases.
abstract: NtdA from Bacillus subtilis is a sugar aminotransferase that catalyzes the pyridoxal phosphate-dependent equatorial transamination of 3-oxo-α-D-glucose 6-phosphate to form α-D-kanosamine 6-phosphate. The crystal structure of NtdA shows that NtdA shares the common aspartate aminotransferase fold (Type 1) with residues from both monomers forming the active site. The crystal structures of NtdA alone, co-crystallized with the product α-D-kanosamine 6-phosphate, and incubated with the amine donor glutamate reveal three key structures in the mechanistic pathway of NtdA. The structure of NtdA alone reveals the internal aldimine form of NtdA with the cofactor pyridoxal phosphate covalently attached to Lys-247. The addition of glutamate results in formation of pyridoxamine phosphate. Co-crystallization with kanosamine 6-phosphate results in the formation of the external aldimine. Only α-D-kanosamine 6-phosphate is observed in the active site of NtdA, not the β-anomer. A comparison of the structure and sequence of NtdA with other sugar aminotransferases enables us to propose that the VIβ family of aminotransferases should be divided into subfamilies based on the catalytic lysine motif.
authors.affiliation: Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: Karin E
authors.initials: KE
authors.lastname: van Straaten
authors.affiliation: Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: Jong Bum
authors.initials: JB
authors.lastname: Ko
authors.affiliation: Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Jagdhane
authors.affiliation: Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: Shazia
authors.initials: S
authors.lastname: Anjum
authors.affiliation: Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: David R J
authors.initials: DRJ
authors.lastname: Palmer
authors.affiliation: Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada. Electronic address: david.sanders@usask.ca.
authors.forename: David A R
authors.initials: DAR
authors.lastname: Sanders
mesh_terms: D020816:Amino Acid Motifs; D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005944:Glucosamine / Q000096:biosynthesis / Q000737:chemistry; D011732:Pyridoxal Phosphate / Q000737:chemistry / Q000378:metabolism; D011733:Pyridoxamine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D040681:Structural Homology, Protein; D000637:Transaminases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C014968:kanosamine; D011732:Pyridoxal Phosphate; D011733:Pyridoxamine; D000637:Transaminases; D005944:Glucosamine; C010627:pyridoxamine phosphate
keywords: Antibiotics; Carbohydrate; Cell Wall; Crystal Structure; Enzymes; Kanosamine; Transaminase; X-ray Crystallography